RU2295793C2 - Adjustable-voltage transformer unit for ac electrified railway transport - Google Patents

Abstract

FIELD: electrical engineering; transformer units for electrified railway transport.

SUBSTANCE: proposed transformer unit has three-phase transformer incorporating primary winding and secondary winding whose two finishing phase leads are interconnected to form common point and starting leads are designed for connection to supply mains. Novelty is introduction of two booster transformers; secondary winding of each of them has at least one voltage regulation device. Each booster transformer has finishing lead of its secondary winding connected to starting lead of respective secondary-winding phase of three-phase transformer and starting lead, to respective section of contact system. Common point of finishing leads of two secondary-winding phases are connected to track rail.

EFFECT: reduced currents and power loss in contact system, improved balancing of supply mains phase currents due to ability of voltage regulation.

1 cl, 5 dwg

Description

The invention relates to electrical engineering, in particular to transformer building, and can find application in transformer units with voltage regulation, designed for electrified AC railways.

Known transformer unit with voltage regulation for electrified railways of alternating current, containing a three-phase traction transformer having a primary winding connected to a star, and a secondary winding connected to a triangle, each of the two vertices of which is connected to one of two sections, isolated from each other, contact network, and the third - to the traction rail [L.1].

The transformer unit described in [L.1] does not provide separate and necessary for each section of the contact network voltage regulation of AC electrified railways and is characterized by an uneven load of the three phases of the primary winding connected to a three-phase supply system and dependent on the uneven load of the three phases of the secondary winding three-phase traction transformer even with a symmetrical load from electric locomotives in two sections of the contact network connected to two vertices of a triangular and formed by the three phases of the secondary winding. As a result of this, there is always an asymmetric operating mode of a three-phase traction transformer and, accordingly, an asymmetric uneven load of a three-phase power supply system, the requirements of which for load balancing are strictly defined by regulatory documents, in particular GOST 13109-97. Electric Energy. Electromagnetic compatibility of technical equipment. Quality standards for electric energy in power supply systems, general purpose.

A transformer assembly for electrified AC railways is also known, comprising a three-phase traction transformer having a primary winding connected in a triangle and a secondary winding connected in a star, the beginning of the windings of two phases of the secondary winding are connected to the contact network, and the beginning of the third phase to the traction rail [L.2].

The transformer unit described in [L.2], as well as the transformer unit according to [L.1], does not provide the necessary requirements for the voltage regulation of AC electrified railways separated by sections of the contact network, as well as the transformer unit according to [L.1 ] is characterized by the uneven load of the three-phase system formed by the primary and secondary windings of the three-phase traction transformer, and therefore, the asymmetric uneven load of the three-phase power supply system. Phase "b" of the three-phase traction transformer is less loaded than the other two phases, since it is connected to the sections of the contact network at both ends and does not work on the load.

The invention solves the problem of creating a transformer unit with voltage regulation for electrified railways, characterized by the possibility of equal or separate voltage regulation in each of the two sections of the contact network, which allows to reduce currents and losses of electric energy by increasing the voltage in the contact network with the same power consumed by electric locomotives in the contact network and improve the balancing of the phase currents of the supply network.

To solve the problem in a transformer unit with voltage regulation for electrified AC railways, containing a three-phase traction transformer having a primary winding and a secondary winding, the ends of the windings of two phases of which are connected to each other, forming a common point, and the beginning is intended to be connected to a contact network , it is proposed according to the present invention to introduce two booster transformers, the end of the secondary winding of each of which is connected to the beginning of the winding, respectively the phase of the secondary winding of the three-phase traction transformer, and the beginning of the secondary winding of each booster transformer is connected to one of the two sections of the contact network, while the common point of connection of the ends of the windings of the two phases of the secondary winding of the three-phase traction transformer is connected to the traction rail; and the secondary winding of each of the boost boost transformers should be equipped with at least one voltage regulation device.

The invention is illustrated by drawings, on which: FIG. 1 is an electrical schematic diagram of the inventive transformer unit with voltage regulation for electrified AC railways; figure 2 - dependence of the magnitude of the currents of the phases of the supply network of the inventive transformer unit: figa - with an asymmetric load (left and right), figb - with a symmetrical load; figure 3 - dependence of the magnitude of the currents of the phases of the supply network known in accordance with [L.1] of the transformer unit: figa - with an asymmetric load (left and right), figb - with a symmetrical load.

A voltage-controlled transformer unit for electrified AC railways comprises a three-phase traction transformer 1.

The primary winding 2 of the three-phase traction transformer 1 is connected to a star.

Secondary winding 3 has two phases: 4 and 5 with ends 6 and 7 and beginnings 8 and 9, respectively: i.e. phase 4 has an end of 6 and a beginning of 8, and phase 5 has an end of 7 and a beginning of 9.

The end 6 of phase 4 of the secondary winding 3 is connected to the end 7 of phase 5 of the secondary winding 3, forming a common point 10 connected to the traction rail 11.

The transformer unit also contains two booster transformers 12 and 13 having secondary windings, respectively: booster transformer 12 - secondary winding 14, booster transformer 13 - secondary winding 15. Secondary windings 14 and 15 of booster transformers 12 and 13 respectively have beginnings and ends: secondary the winding 14 has a beginning 16 and an end 17, the secondary winding 15 has a beginning 18 and an end 19.

The ends 17 and 19 of the secondary windings 14 and 15 of the boost transformers 12 and 13 are connected to the beginnings 8 and 9 of the corresponding phases 4 and 5 of the secondary winding 3 of the three-phase traction transformer 1. In particular, the end 17 of the secondary winding 14 of the boost transformer 12 is connected to the beginning of the 8 phase winding 4 secondary windings 3 three-phase traction transformer 1; the end 19 of the secondary winding 15 of the boost transformer 13 is connected to the beginning 9 of the phase 5 winding of the secondary winding 3 of the three-phase traction transformer 1. The beginnings 16 and 18 of the secondary windings 14 and 15 of the boost transformers 12 and 13 are connected to the corresponding section of the contact network. In particular, the beginning 16 of the secondary winding 14 of the boost transformer 12 is connected to the section 20 of the contact network; the beginning 18 of the secondary winding 15 of the boost transformer 13 is connected to the section 21 of the contact network.

The voltage regulation devices 22 and 23 of the secondary windings 14 and 15 of the boost transformers 12 and 13 are turned on in such a way as to ensure a change in the number of turns of the secondary windings of these transformers.

From the dependences of the phase currents of the three-phase supply network on the values of the load currents in the contact network presented in FIGS. 2 and 3, it follows that by connecting the boost boost transformers to the phases “AB” and “BC” of the three-phase supply network, an additional current load of phase “B” occurs supply network and, accordingly, a more uniform current load of the phases of the supply network. So, with a symmetrical identical load in sections 20 and 21 (figure 1) of the contact network, the current in phase "B" of the supply network is less than the currents in phases "A" and "C" in the power circuit of the contact network from a three-phase traction transformer according to [L. 1] 2.37 times, and in the inventive transformer unit - 1.56 times. With an asymmetric load (the presence of a load current in one section and the absence in another), the currents of the phases of the supply network differ almost identically, respectively 2.5 and 2.9 times.

The introduction into the transformer unit of two booster transformers with the connection of their secondary windings in series and in accordance with the secondary windings of a three-phase traction transformer provides a summation of the voltages of the secondary windings of the three-phase traction transformer and booster transformers and, accordingly, a voltage increase in the contact network to 57 V against 47 V in the transformer unit in accordance with [L.1], and in case of equality of the power received from the system of the order of 2580 W, it will lead to a decrease eye from 52 A to 40.8 A, i.e. by 21%. A decrease in the contact current network will, in turn, lead to a reduction in the loss of electric energy in it. In addition, the exclusion of one of the phases of the secondary winding of a three-phase traction transformer will significantly reduce the cost of manufacturing a transformer unit.

Thus, the claimed solution will provide:

- voltage increase in the contact network;

- reduction of load currents and losses of electric energy in the traction network with constant power consumption;

- improving the symmetry of phase currents.

In accordance with the claimed decision, technical documentation has been developed. A prototype transformer unit was manufactured and tested. The test results confirmed the operability of the transformer unit and the wide possibilities of its practical application in the future. Currently, work is underway on the manufacture of an industrial design of a transformer unit.

Literature

1. K.G. Marquardt. Power supply of electrified railways. Moscow. "Transport", 1982, pp. 25-29; 245-248.

2. A.S. Avatkov. Electrification of railways on a single-phase current of industrial frequency. Moscow. Transzheldorizdat, 1958, p. 218, Fig. 202.

Claims (1)

A voltage-controlled transformer unit for alternating current electrified railways, comprising a three-phase transformer having a primary winding and a secondary winding, the ends of the windings of two phases of which are interconnected to form a common point, and the beginning is intended to be connected to a contact network, characterized in that it contains two booster transformers, the end of the secondary winding of each of which is connected to the beginning of the winding of the corresponding phase of the secondary winding of a three-phase transformer, and the beginning of the secondary winding of each booster transformer is connected to one of two sections of the contact network, while the common point of connection of the ends of the windings of the two phases of the secondary winding of the three-phase transformer is connected to the traction rail, while the secondary winding of each of the booster transformers contains at least one regulation device voltage.

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